Easy to defend mega land with harsh winters (but not so harsh anymore as they were during those failed campaigns), especially when both defeated invading armies severely underestimated... cold weather. Nobody is really invading russia here, whole world just wants to be left alone from them, including all former soviet republics (funnily this includes Belarus too).

That's not saying anything about their offensive capabilities, which as whole world sees are a fraction of what was thought about them. They really are supremely ineffective, corrupt and lazy in numbers and levels that cripple whole war for them. They can't produce enough new armed vehicles and their stockpiles from cold war are running very thin as per independent satellite analyses, they use stolen motorbikes, donkeys and golf karts for troopers now (with corresponding death rate). Their nuclear weapons are just a guarantee they won't be attacked on Moscow conventionally or nuclear in any way, nothing more. As we see all other 'doctrines' and 'red lines' fell apart with long lasting incursion in Kursk so that was just an empty bullshit.

They know all this, their country is falling into inflation spiral which can easily end up with people's revolt and I believe puttin' realizes how fragile his relatively soft power grip on russia is. Plus he has positioned himself as an arbiter between various power clans within his hierarchy, not as a single supreme single ruler whom everybody fears for life like in North Korea for example. He desperately needs to finish this war within a year or two since he is an extremely paranoid person. But he has some sort of effective reach or control over orange man and we saw what we saw, who knows why.